It is 40 years since Garry Trudeau first drew the Doonesbury strip that is syndicated to almost 1,400 newspapers across the world, including The Guardian.

Since October 1970, his recurring characters - such as Mike Doonesbury, BD, Boopsie, Mark Slackmeyer, Joanie Caucus and Zonker Harris plus an array of real-life political and military figures - have entertained millions.

The strip, which has documented the baby boom generation's advance through life, manages to be both very funny and politically acute.

In 1975, Trudeau became the first comic strip cartoonist to win a Pulitzer prize. But he has always maintained a low profile and rarely answers questions about his work.

You can watch it here, and there's also a full transcript. A couple of highlights...

Asked what Doonesbury is about, Trudeau explained that "it began as a kind of diary of my generation coming of age... It was sold as kind of dispatches from the front lines of the counter-cultural wars."

Brown: Were the central characters therefore people that you knew, or knew of, and then exaggerated?

Trudeau: "Yes... And, in many cases, I would take someone who was wholly admirable and turn them into someone who was completely reprehensible."

Brown: "When you went through all this 40 years of strips to put this [book] together, did you feel a coherence... to the tale?"

Trudeau: "Yes, it sort of took me by surprise that it had a kind of novelistic totality that certainly was unintentional... I'm a short-order cook. I'm just trying to get through the week."